This invention relates to a cooling capsule for disc-shaped semi-conductor components. More particularly, it relates to cooling capsules in which two cover dishes of heat-conducting material, having approximately flat and parallel faces, provide a thermally conducting connection to at least one semiconductor component and in which a core, fastened in a recess within each cover dish, defines a flow channel, from an inlet to an outlet in the side wall of the cooling capsule, for a liquid coolant.
A cooling capsule of this type is described in German Patent No. 2 160 302. In a known cooling capsule, both the cover dishes and the core are cylindrical and have the same diameter. The side wall of the cooling capsule is formed by the side wall of the core and the inlet and outlet openings lead to associated holes in the cylindrical core and go from one end face of the core to the other. Each cover dish is placed on an end face of the core and annular concentric grooves, arranged as recesses in each cover dish, serve as flow paths which connect the two holes in the core. The cylindrical core and the cover dishes having flow paths are sealed together, liquid-tight, by hollow-rivet joints. These cooling capsules are used for cooling individual disc-type thyristors or disc-type diodes; the thyristors and diodes are each clamped between two cooling capsules.
The cooling capsules are used in so-called thyristor stacks for cooling several disc-type thyristors. In such thyristor stacks, disc-type thyristors are stacked and clamped side by side, with a heat sink inserted on each side of a disc-type thyristor and resting against the heat transfer surface of the disc-type thyristor. Such a thyristor stack is shown in German Patent 1 914 790.
The thermal resistance and, thereby, the cooling capacity of a cooling capsule depend substantially on the size of the metal surface past which the coolant flows. In the known cooling capsule, a multiplicity of concentric grooves are therefore milled into the two cover dishes as flow paths. The coolant in these flow paths is continuously deflected (changing direction), which, of necessity, causes a pressure loss in the coolant. The possible cross-section of the flow paths and the length overall of the flow path is therefore circumscribed. Therefore, the maximum obtainable heat transfer, using the largest area possible between the metal of the cooling capsule and the coolant, is nevertheless limited, in the known cooling capsule, by pressure loss across the coolant path due to the structure used.
It is an object of this invention to provide a cooling capsule of the type described above in which, when a large heat transfer area is used, pressure losses are, to all intents and purposes, avoided.